Instructions: Blend Garlic, ½ cup Softened Butter, ½ tsp. salt set aside for use on the bread. Set aside. In a separate bowl mix sour cream, mayo, horseradish and white pepper. Refrigerate until ready to use. Mix together Ground beef, black peppercorns, Worcestershire sauce, onion flakes and 2 tsp salt with gloved hands until just combined. Divide beef mixture into 6 equal portions and flatten into patties @ 1 inch thick. Heat all burners of a BBQ Pro 3 burner gas grill with cast iron grates to high and place the sauté pan in the center of the grill. Pour in 1 tbsp Olive Oil and add remaining ½ cup butter, swirl the pan over the heat so the butter does not burn. Once, the butter has melted add the mushrooms and toss to evenly coat with the heated oil. Sauté the mushrooms until tender 3-5 minutes. Add brandy, allow to cook down and reduce by half. Add beef broth allow to cook down and reduce by half. son with 1 tsp. Salt. Remove from the grill, set aside. Brush the grill grates with the remaining olive oil. Place the beef patties on the hot grill grates cook 2-3 minutes on each side. Remove from grill and cover with aluminum foil until ready to assemble the burgers. Reduce grill heat to low and cover grates with aluminum foil. Spread each piece of bread with a thin layer of garlic butter and place butter side down on the foil over the grill grates until toasted Assemble Mushroom Au Poivre Burgers: Place the bottom half of the bread slices on 6 plates, spoon the horseradish sauce on each slice, top with a grilled beef pattie, top each pattie with an equal amount of the mushroom mixture and finish with the remaining garlic bread slices